The present invention relates to a high molecular sensor and manufacturing method thereof in which polypyrrole which is a conductive high molecule is electrochemically polymerized and then reduced and thereby ionic conductivity is given so that humidity sensibility is made to be excellent.
High molecules having conjugated structures exhibit an electric conductivity essentially by doping and include polyacetylene, polyparaphenylene, polyaniline, polyacene, polypyrrole, polythiophene, and polyfuran. These conductive high molecules are used for pH sensors, pressure sensors, sulphuric acid concentration sensors, oxygen and bionic sensors, and glucose sensors and the like. Examples of such sensors are alcohol and gas sensors as well as humidity sensors. High molecules used for humidity sensors (Japanese laid-open patent publication nos. 88-133050, 88-122758, 85-201244) are polyfuran, polythiophene, polyphyrrole, heterocyclic and compounds of their derivatives. In those publications, a simple structure of glass coated with indium tin oxide (ITO) was used for an electrode of the sensor, and a separate reducing process for improving ionic conductivity was not executed. In those examples, since there is a limitation in humidity sensing speed and humidity measuring range, post-processing was required for improving the precisely-made sensor structure and ionic conductivity.
Polypyrrole, polythiophene, polyfuran and the like which are a kind of heterocyclic compound are electrochemically polymerized, and at the same time, a doping occurs to thereby produce electric conductivity. Therefore, the electric conduction operated in complex. Since the ionic conductivity produced by a non-crystalloid within the high molecule is weaker than electronic conductivity, the conductivity is substantially electronic conductivity.